Image Credit: All drawings excluding center top were borrowed from old Lao stamps. Name of the artist is not known and was not published on the stamps.
It's used for crushing, grinding, pounding and mixing ingredients, depending on how intense you use it. The more common one is the table-top, hand drive one (at center top). This is the one found in most Lao kitchens and is the primary tool used to make Lao sauces, papaya salad and for pounding rice.
Through history, the Lao have used it in its varying forms from foot operated, hand driven and even water powered as shown above.